B2600i starting problem....help please!

My daughters 1990 B2600i wont start...here is what has happened and what I have done.......About a month ago I got in it to drive it and it wouldnt start. You could hear the solenoid engaging but it would not turn over.....I tried 2 more "new" starters and a new battery...still no change.........I found a relay mounted just behind the battery and next to the main fuses......I unplugged it and plugged it back in...the truck started and ran fine for a few weeks.....It quit starting again and doing the same thing so I did the same thing and it started again.....A few weeks go by and it does it again....Now I cant get it to start.....I tried another relay I had from a parts truck.....It started fine...tried it five times and it started great...Ok I thouht I found the problem (bad Relay). I got in it this morning to drive it and it wont start....doing the same thing again........HELP!!!!! I dont know where to go from here.

I think that is the same relay that was tripping on me... I had a problem at the top of the clutch pedal. When I engaged the clutch, the very top of the pedal was shorting out wires under the dash. I corrected that problem and things have been good for the last 3 years...

Just a thought.

This is an automatic....I guess I should have said that...sorry. I messed with it some more and got it to work for one day.....Again this morning it wouldnt start.